To improve the manufacturing accuracy of composite stiffened panels， this paper study the structural composition of composite stiffened panels based on the co-bonded forming process of composite stiffened panels. A calculation model is derived for the amount of prepreg required to fill the R region of the stiffeners， achieving precise filling of the R zone of co-bonded composite stiffened panels. The structural design of the molding fixture for composite stiffened panels is optimized， improving the positioning accuracy of the positioning pins and achieving precise control of the stiffener axis line position. A cutting template is made for the outline of the stiffener to achieve accurate cutting of the stiffener edge distance. By precisely filling the R zone of the stiffeners， precisely controlling the stiffener axis line position， and accurately cutting the stiffener edge distance， the precise manufacturing of composite stiffened panels with stiffeners is achieved.